well something changed i had an older version from when you just added the 03 Axle design going from the side to side assembly to the top down for strength and using the newest stl files i have the same issue that Marcus24 commented about. the difference with Marcus24 and me is i forced the gears to destruction so i could see the failure. the teeth are not engaging deep enough with each other under load and the tops of the diff gear teeth are snapping the tops off. all the bevel gears are fine and no problem with the input gear nor the diff gear bevels.
before destroying the gears i started to feel them by hand and there was more backlash then i would of liked between the diff and countergear which is why i suspected they were skipping on each other.